With very great difficulty - I've just replaced the element on mine, and it's taken all day. The machine is held together with staples and rivets, which have to be drilled out, and then part of the framing has to be cut away to get at the back of two of the said rivets. I bolted mine back together rather than re-riveting it.
If I'd thought of it, I would have taken a photo before removing each component, because I did find the jigsaw of putting it back together quite challenging. Even now, I've left out a piece of foam that's supposed to cover the temperature sensor. It remains to be seen whether that causes the new element to burn out more quickly than the last.
I got the new element by ordering it on line from Corby. But that was about 6 months ago, and they no longer feature it on their website.
When this element goes, I will throw the machine away and buy a new one. When they work they are jolly good. But to say that their design/construction is primitive is to put it very mildly!!
Tony Ares, August 2012